Pump arrangement in a transmission

ABSTRACT

A pump arrangement for a transmission in which an integrated pump rotates with a common drive shaft (6) having a free end, supported via a shaft bearing (8), carrying a connection part (12) for accommodating a power take off shaft (14), the connection part is provided with a spline or wedge arrangement for driving both the power take off shaft (14), when attached thereto, and a pump rotor (16) of the integrated pump, a pump stator (3) is snugly positioned in a housing wall opening (2) and is provided with a bearing neck (7) supporting the shaft bearing (8), a fed inlet and a discharge outlet for the pump stator are provided in a housing wall (1) and a housing cover (19), which has a central opening (21) accommodating the connection part (12), covers a face of the pump stator adjacent the take off side.

The invention concerns a pump arrangement in a transmission according tothe preamble of claim 1 and is based on DE-C 25 29 248, FIG. 1, position26, 27.

According to the above, it is already known in transmissions havingintegrated pumps and optionally connectable power take-off to drive, forexample, both the pump required for the oil supply of a converter and apressure switch, and a direct power take-off by means of a common driveshaft which has on its free end, in a housing wall, a bearing which,together with a connection part of the power take-off, is fixed by ahousing wall cover.

The former type of arrangement, of course, provides that the pump besituated in a manner of difficult access in the interior of thetransmission and with the supports of its stator on the intermediatewalls. See also the applicant's prospectus "ZF-Hydromedia-ReversingTransmission" F 43 0751/RT 3240, p.1.

This kind of arrangement required at least one separate central bearingfor the pump and costly molds for the transmission housing on account ofthe oil channels to be provided in the interior of the transmission inintermediate walls and for shock and vibrations absorption of the pumpworking at a distance from the wall reinforcements.

On the basis of the above the problems to be solved, the invention isseen as providing a pump arrangement which not only provides betteraccessibility (without disassembling the transmission) but also makespossible a simplified construction of the transmission housing withimproved absorption of vibrations and arrangement of the oil channels.

The solution is obtained with the features of claim 1 insofar as due tothe combination of the power take-off with the pump, the ,latter nowrests in a main bearing of the drive shaft directly on an externalhousing wall in which integrally cast channels contribute to morevibration absorption. Here, the complete pump can be simply and quicklychanged together with the shaft bearing only after releasing a flangeconnection and a central screw without engaging the transmissiontractions or disassembling the whole transmission. It is also favorablethat the pump rotor has its own bearing on a connection part that isdismountable together with it, and the pump stator is directly attachedto the housing wall so that no separate supporting ribs have to beprovided therefore in the transmission housing.

With this arrangement, it is as a rule possible to omit a centralsupport of the drive shaft by additional bearings in the interior of thehousing, and a possibility of common bearing adjustment results thatsaves work and parts by fastening the connection part for the powertake-off shaft.

Other advantageous improvements result with the embodiments defined inthe sub-claims.

When the connection part, such as hollow shaft that drives the pumprotor, is provided with an internal spline inserted in the drive shaft,the power take-off shaft can be simply introduced, when needed, and thepump rotor can be fixed with special ease axially through the housingcover. When the connection part here serves for fastening a pump rotorbearing, the latter is also easily controllable from the outside.

By means of a piston-like pump stator, it is also reliably possible toseal the transmission housing by radial seals (piston or O-rings)independently of the variations of length of the shaft.

When omitting the precise processing of the internal wall of the openingof the transmission housing, the possibility of providing in the housingcover an axial sealing with respect to the pump stator is offered.

By providing a detachable axial support both between shaft and theconnection part and between the later and the bearing, an especiallysimple fastening of pump and stator is obtained with the possibility ofeasy disassembling.

By a flange-like axial fastening of the pump stator on the housingcover, the complete pump, together with the housing cover and with thebearing on the connection part, can be drawn out from the housing wallopening without being disassembled and, if needed, be replaced as soonas the housing cover of the housing wall and a central screw, serving asan axial support of the connection part, with circlips between shaft andconnection part are detached.

Even though the advantages of this pump arrangement are independent ofthe design of the pump, it is possible in the simplest mannerfundamentally to realize them with rotational pumps such as gear androtation piston pumps.

The invention is not confined to the combination of features of theclaims. From the claims and individual features thereof, other logicalpossible combinations result to the expert as the problem arises.

The invention is explained in detail herebelow with reference to thedrawing of an embodiment.

FIG. 1 shows a cross-sectional arrangement of the pump integrated intothe housing wall of a transmission.

In FIG. 1, a housing wall 1 is provided with an opening 2 large enoughto surround closely a pump stator 3 inserted therein piston-like fromthe outside. In the housing wall 1, oil channels 4 are provided whichhave corresponding connections with the pump stator discharge 5. Thelatter is penetrated along its longitudinal axis by a common drive shaft6 which it guides by means of a bearing 8 fixed on the transmission sidein a bearing neck 7. Said bearing is radially supported by its internalring both on a ring collar 10 of the shaft 6, which opens toward thefree end 9, and on a ring collar 11 of a connection part 12, similar toa hollow shaft, which opens toward the shaft 6, said connection partbeing non-rotatable with respect to the shaft 6 via a multi-gear splineconnection 13 having an open end external side in which is insertable apower take-off shaft 14 when needed. The connection part 12 likewisehas, on its external side, a driver spline 15, or in the instantembodiment a wedging, capable of carrying a pump rotor 16 attached tothe pump stator 3 along in the direction of rotation. The pump stator 3is fastened to a housing cover 19 on the take-off side by fixing screws17 and inserted piston-like in the housing wall 1 and fitted, forexample, by means of O-rings or piston rings 18. Instead of radialseals, gaskets for the housing cover can be provided. The cover 19 abutsaxially close on the front side opening of the pump stator 3, on thetake-off side, and has a central opening 21 through which projects, onthe take-off side, the connection part 12 for the power take-off 14. Apump rotor bearing 22 is provided in the central opening 21 which ispreferably designed as needle bearing and likewise can be wellcontrolled from the outside.

The housing cover 19 is fastened, from the outside, to a processedsurface of the transmission housing wall 1 by means of several fixingscrews 23 which, depending on the application, can additionally carry anintermediate flange 24 which is set up either for accommodating anadditional unit 25 (pump, lifting jack, or the like) that can be drivenby the power take-off 14 or as seal cover of the housing wall opening 2which is detachable independently of the pump stator 3. If an additionaloil pump is operated by the power take-off, no special sealing from thepump stator 3 is needed within the housing wall 1.

The axial support 29 of the connection part 12, opposite the free shaftend 9, is detachable by means of circlips 26 and a counter disc 27 heldby a central screw 28.

Several circlips 26 are inserted in an internal annular groove in theinternal spline 13 of the connection part 12 so as to abut on the frontedge of the take-off side of the free shaft end 9. For reinforcement, acounter disc 27 fixed to the shaft 6 by the central screw 28 is providedover the circlips 26.

In the construction according to the invention, for disassembling thepump 3, 16 and/or the bearing 6 it is only necessary to release thefixing screws 23 and the central screw 28 and to draw the circlips 26before the complete housing, including the shaft bearing 8 and cover 19,can be removed from the wall opening 2 and the shaft 6. Since the driveshaft is supported, when parked, by gears or an additional bearing onthe drive side, the complete pump-bearing structure can be easilyinserted after reconstruction without another assembly opening 2 beingneed in the transmission housing 1 to introduce the shaft 8 therethroughinto the opening of the bearing 8.

REFERENCE NUMERALS

1--housing wall

2--opening of 1

3--pump stator

4--oil channels in 1

5--connections on 3

6--drive shaft

7--bearing neck on 3

8--shaft bearing of 6

9--free end of 6

10--ring collar on 9

11--ring collar on 12

12--connection part for 14

13--multiple-tooth spline connection of 9 and 12

14--power take-off

15--external drag spline of 12

16--pump rotor

17--fixing screws

18--seals of 16

19--housing cover

20

21--central opening of 19

22--pump-rotor bearing

23--fixing screws for 19

24--intermediate or cover flange

25--installation unit with 14

26--circlips

27--counter disc

28--central screw

29--axial support of 12 against 9

We claim:
 1. A pump arrangement in a transmission in which an integratedpump rotates with a drive shaft (6) having a free end (9) thereof whichis supported by a shaft bearing (8), engaging a housing wall (1), and aconnection part (12), for accommodating a power take-off shaft (14), islocated by a housing cover (19) attached to said housing wall(1),characterized in that said connection part (12) is provided withmeans for driving both a power take-off shaft (14), when attachedthereto, and a pump rotor (16) of said integrated pump, said connectionpart (12) and said pump rotor (16) are surrounded by a pump stator (3)snugly positioned in an opening (2) of said housing wall and providedwith a bearing neck (7) which carries said shaft bearing (8), a feedinlet and a discharge outlet for said pump stator (3) are provided insaid housing wall (1), and said housing cover (19) covers a face of saidpump stator (3), on a take-off side of said integrated pump remote fromsaid drive shaft (6), and has a central opening (21) facilitatingengagement between said connection part (12) and a said power take-offshaft (14), when attached thereto.
 2. An arrangement according to claim1, wherein said pump rotor (16) has a second bearing (22) surrounding,adjacent the take-off side, a portion of said connection part (12). 3.An arrangement according to claim 1, wherein said pump stator (3) isfitted in said housing wall opening (2) and has a sealing element (18)located between said housing cover and said housing wall (1).
 4. Anarrangement according to claim 1, wherein said connection part (12)comprises an elongate hollow shaft having external means for drivingsaid pump rotor (16) and an internal spline engagable with a said powertake-off shaft (14), adjacent one end thereof, and meshing with anexternal spline on the free end of said drive shaft (6), adjacent theother end thereof.
 5. An arrangement according to claim 1, wherein saidconnection part (12) is secured by a detachable axial support (29) withrespect to both said drive shaft (6) and said shaft bearing (8).
 6. Anarrangement according to claim 5, wherein said pump stator (3) isfastened to said housing cover (19) so that after detaching said housingcover (19) from said housing wall (1) and removing said detachable axialsupport (29) of said connection part (12), said housing cover (19) isremovable, from the free end of said drive shaft (6), together with saidpump rotor (16), said pump stator (3) and said bearing (8) as a singleunit and can be withdrawn from said housing wall opening (2).
 7. Anarrangement according to claim 1, further comprising a said powertake-off shaft (14) engaging said connection part (12).